1. Terms and Technology
Gas and/or oil wells produce various ratios of fluid mixtures. These wells represent any source of a fluid mixture processed by the present invention. Only for the purpose of disclosing the preferred embodiment of the present invention, it will be the assumption that a gas-oil ratio (GOR) of at least 5000 scf/barrel will be processed by application of the invention.
The separator refers to a vessel having an input for the mixture to be separated and an output for each of the components of the mixture after they are separated from each other. Although not limited to such, the vessel of the separator with which the invention is disclosed is a steel cylinder oriented to have its axis horizontally extended. Each end of the cylinder is closed by a dished head which may be specifically elliptical or hemispherical; however, normally the elliptical shape is preferred. An entrance conduit is formed through the front head. The outlet conduits may or may not be formed in the second head. In all events, the structure embodying the present invention is mounted internally, most conveniently within the dished front head. Dimensionally, the radius of these shells may range upwardly from 12", with lengths upward from 5 feet, and a wall thickness commensurate with the pressure anticipated from a particular well production.
The embodiment of the invention is noncentrifugal. There is a genre of separators having internals which generate centrifugal forces on the mixtures processed. This class of input structure is to be distinguished from the input structure in which the present invention is embodied. Specifically, the present embodiment of the invention may fall under that class of structure which can be termed "impact" structure, and which dissipates the momentum of the flowing energy of the mixture as a stream.
2. The Operational Environment
The flowing fluid mixture enters its separator at the pipeline velocities having a kinetic energy related K-factor of typically 10. The well-known K-factor equation is: ##EQU1## The typical or conventional separator processing a mixture of liquid and gas, has a mist extractor structure in the separating gas flow path which cannot tolerate a K-factor above 0.6. It is the function of the momentum absorber to reduce whatever the pipeline velocity is to the typical superficial K-factor of 0.6. The importance of the function and structure of the momentum absorber has been given little research and development in the face of a serious need for improvement.
In liquid/gas separators, probably the most familiar impact momentum absorber is the rat trap. Also, in general use is the dished head or channel reflector as a target for the incoming stream. These targets are often used with a lower horizontal plate "table". The table prevents high velocity downward streams of gas from picking up previously separated surface liquid below the target. These momentum absorbers produce localized streams with velocities as high as 5 times the design superficial velocity. The result is called maldistribution, non-uniformity of the flow profile, or channeling in the gas flow path. This maldistribution picks up surface liquid and loads up the mist extractor in local areas with high flow rates of gas and liquid. The result is liquid carryover from the mist extractor.
It has long been the practice to form an inlet in the dished head of the separator above the centerline of the horizontal shell. The impact momentum absorber structure has been traditionally mounted within the dished head to receive the inlet stream. There was the elementary hope that the gas would be efficiently released above the lower body of collected liquid separated from the gas and gravitate downward to join the previously separated body of liquid. Recently, economic considerations have motivated centering the inlet to reduce the fabrication cost of the separator. This evaluation became the catalyst for systematic investigation of the true effectiveness, or efficiency, of the conventional impact momentum absorber structure.
There is need for an internal impact structure for a fluid mixture separator with greatly reduced restriction to throughput of the flow stream, while ensuring at least two 180.degree. reversals of direction, and sufficient volume for the resultant eddies in the stream of the mixture to dissipate their flow velocity into heat energy. Further, there is need for strategically placed diverters to prevent strong, localized flow velocities in the subsequent flow area downstream of the impact structure.